As we learned on yesterday’s daf (=page) the halakhot of shevu’at ha-eidut – the laws governing cases where a person refuses to offer testimony, swearing that he does not have information that would be useful in court – only apply to monetary cases. Rabbi Yossi ha-Galili derives this from the passage in the Torah (Sefer Vayikra 5:1) where we see that these laws apply only in cases where it is possible that a witness can see without knowing or know without seeing. Such criteria can only be met in monetary cases.
In today’s Gemara, Rav Papa suggests to Abayye that according to Rav Aha there may be cases where we find that witnesses can fulfill the need to know even without seeing, even in cases other than monetary cases. For with regard to a case where we see a camel in heat which becomes violent, should we discover that a different camel was trampled to death we can say with certainty that it was the camel who had been acting strangely who did it. Similarly Rav Aha would rule in a case where we find a person stabbed to death and another standing above him holding the bloody knife, that we can act with certainty and rule that he is the murderer, even if the witness did not see him commit the crime.
The Gemara rejects this assertion, arguing that Rabbi Yossi ha-Galili might accept Rav Aha’s ruling, but that we will still be unable to find a case where the witness sees the event but does not know the details in anything but monetary cases. This cannot be the case in capital cases, since the witness may see the murder take place, but he cannot know whether the victim was Jewish or not or whether the victim was healthy or, perhaps, he was a terefah who would not live out the year, and therefore the murderer would not be liable.
Tosafot point out that ordinarily we do not concern ourselves with the unlikely possibility that someone might be a terefah, since the vast majority of people are healthy. They answer that we must be talking about a case where there are two people in front of us and we know that one of them is a terefah. According to the Ramban we are discussing a case where the victim had a clear condition that may, or may not, have made him a terefah.